Step-by-step evaluation of a hypothetical six-axis system where all motion is driven directly from the real-time vehicle physics engine
Educational demonstration only. No real products, manufacturers, or organizations are referenced. This hypothetical system was constructed to illustrate what an In-the-Loop classification looks like from the inside.
Educational reference only. This evaluation is a hypothetical demonstration. The system described does not exist and is not based on any real product. The classification shown here does not apply to any real simulation system. For the evaluation methodology this demonstration is based on, see Evaluation Process.
Reference System A is a hypothetical six-axis motion platform intended to represent the class of systems where all motion output is causatively derived from the real-time vehicle physics simulation. It was constructed to demonstrate what the evidence package and criterion review look like for a system that fully satisfies the In-the-Loop structural requirements.
The defining architectural feature of this system is the absence of any transformation layer between the physics model output and the actuator command signal. When the vehicle physics model calculates a yaw moment, that calculation produces the actuator command directly. There is no washout filter, no motion cueing algorithm, and no approximation applied before the signal reaches the actuators.
Every SFR evaluation begins with a review of five required evidence inputs. The table below shows what was reviewed for Reference System A, the evidence tier assigned to each input, and a summary of what that input established.
Evidence tiers: Tier 1 = measured telemetry (highest quality); Tier 2 = verified system documentation; Tier 3 = manufacturer-provided specification; Tier 4 = unverified manufacturer claim (lowest).
| Input | Description | Tier | Finding |
|---|---|---|---|
| R1 Motion Telemetry |
Time-stamped actuator command logs cross-referenced with physics model force outputs during reference motion events | Tier 1 | Actuator commands correspond directly to physics outputs within measurement precision. No transformation artifacts detected. |
| R2 Physics Architecture |
System architecture documentation showing signal path from physics engine to motion controller | Tier 2 | Documentation confirms direct causal chain. Physics engine output feeds motion controller input without intermediate processing stage. |
| R3 Actuator Specification |
Engineering specification for each of the six axes, covering control loop architecture and command interface | Tier 2 | Each axis operates on an independent closed-loop control system. No shared actuator path, no cross-axis coupling at the control level. Center-of-mass reference coordinate enforced in motion controller configuration. |
| R4 Synchronization Data |
Timing logs for motion command issuance relative to visual frame render and audio output during four reference motion events | Tier 1 | Motion, visual, and audio outputs confirmed to share a single physics clock. Timing relationships measured within the required synchronization window across all reference events. |
| R5 Control Telemetry |
Logs tracing participant control inputs (steering, throttle, brake) through physics state changes to resulting motion commands | Tier 1 | Control inputs demonstrably affect physics state. Physics state changes produce corresponding motion commands in the expected direction and magnitude. Causal chain from input to motion output is intact and traceable. |
All five required inputs were available. Three inputs were Tier 1 (measured telemetry); two were Tier 2 (verified documentation). No Tier 3 or Tier 4 evidence was relied upon for any criterion. The evidence package is complete and of high quality.
Each criterion is assessed independently using the evidence collected. The result for each criterion is Pass, Fail, or Insufficient Data. All three criteria must pass for an In-the-Loop classification.
R1 (motion telemetry) shows that actuator commands correspond directly to physics model force and moment outputs. R2 (architecture documentation) confirms no intermediate processing stage between physics output and motion controller input.
The motion delivered to the participant originates from the vehicle physics model output at the moment of generation. When the physics model calculates a lateral acceleration event, that calculation produces the corresponding actuator command. No washout filter, motion cueing algorithm, or post-processing layer modifies the signal before it reaches the actuators. The causal relationship between vehicle physics state and participant motion input is direct and unbroken.
Primary evidence: R1 (Tier 1), R2 (Tier 2)
R3 (actuator specification) documents independent closed-loop control for each of the six axes. Architecture documentation confirms center-of-mass reference is enforced in the motion controller configuration. No shared actuator path or cross-axis coupling identified at the control level.
Each of the six axes (surge, sway, heave, roll, pitch, yaw) operates through an independent control loop. A command issued to the yaw axis does not affect the heave or surge axis through any shared mechanical or computational path. Axis independence holds at both the control level and the mechanical level. The reference coordinate used for all rotational and translational calculations is the vehicle center of mass, as specified in the motion controller configuration and confirmed in the architecture documentation.
Primary evidence: R3 (Tier 2)
R1 (motion telemetry) provides motion magnitude and timing data during four reference motion events. R4 (synchronization data) confirms timing relationships between motion and visual output. R5 (control telemetry) confirms the motion outputs correspond to the vehicle events being depicted.
Motion magnitudes and onset timing measured during the four reference motion events (steady-state lateral, transient yaw onset, combined axis, limit-state threshold) are consistent with expected inner-ear stimulus parameters for the depicted vehicle dynamics. Because motion is physics-derived and unmodified (established in Criterion A), the timing and magnitude relationships reflect the actual vehicle physics state. No evidence of systematic magnitude attenuation or timing distortion that would prevent the inner ear from receiving a valid motion signal was identified.
Primary evidence: R1 (Tier 1), R4 (Tier 1), R5 (Tier 1)
All three structural criteria were met. Motion is causatively derived from the vehicle physics model, delivered through independent axes referenced to the vehicle center of mass, with timing and magnitude characteristics consistent with valid physiological stimulation for the depicted vehicle events. The evidence quality is high: three Tier 1 inputs and two Tier 2 inputs. No criterion returned Fail or Insufficient Data.
This reference evaluation illustrates several features of the In-the-Loop classification that are worth understanding clearly.